WPCOM Member < 1.7.6 - Authentication Bypass via 'user_phone'

Description

The WPCOM Member plugin for WordPress is vulnerable to authentication bypass in all versions up to, and including, 1.7.5. This is due to insufficient verification on the 'user_phone' parameter when logging in. This makes it possible for unauthenticated attackers to log in as any existing user on the site, such as an administrator, if SMS login is enabled.